What is a Distal Point
To determine the distal points in your facility you have to have a rudimentary understanding of your water distribution system both cold and warm/hot water systems. For instance do you have one hot water system which feeds the whole site or multiple hot water systems feeding different wings, floors.
Generally, your cold water system will have one entry point to your property, but depending on the size of your facility and water pressure you may have more. Cold water systems generally flows towards outlets and will terminate at the farthest outlet. For your cold water that is your distal point. Depending on the layout of your facility you may have multiple branch lines that terminate, which all are distal points that will require sampling.
Warm water systems are generally are on a loop system which distributes warm water to individual rooms, knowing which way the water flows is essential to determining the distal point as physically the farthest point may not be the distal point.
TMVs or thermostatic mixing valves can act as warm water systems they deliver water at temperatures below scalding temperature.
Hot water systems depending on the size of the facility may have Hot water system that will be similar to your cold water distribution system with the distal point being the farthest point from the Hot water vessel. But if they are larger systems they might be similar to warm water systems with flow and return and there maybe circulation pumps involved too.
Sometimes there can be one-way valves which provide a single direction of flow or bypass systems for use in maintenance scenarios.
So when determining the distal points for sampling it is essential that you have a thorough understanding of how each separate water system you have on site is built.
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